The ensemble averaging is one of the most important concepts for scientific theories as well as practical measurements especially for sound absorption measurements of materials. Applying a technique based on the ensemble averaging, the authors have been developing an in situ measurement method for sound absorption characteristics, surface normal impedance and absorption coefficient; and we call it EA-method, for short. The primary objective of our study was set to measure various building materials' sound absorption characteristics used in room acoustics simulations, especially in wave-based numerical methods. In the successive studies, EA-method showed excellent robustness as well as good reproducibility regardless of measurement places or material types. Herein, further applicability of the EA-method is discussed referring to measurement results of materials conducted at various environments. The measured materials are not only porous-types but also panel-types and resonant-types.
Otsuru et al. (Wed,) studied this question.